1. Field of the Invention
The present invention relates to an emulsion composition that can be made to dry uniformly when applied, or a paint composition in which such an emulsion composition is used, and more specifically, relates to an emulsion composition that can be made to dry uniformly without giving rise to cracking or blistering, etc., when paint having a thick film thickness such as a damping material paint is being dried or is dried at a high temperature, and in addition, can prevent dripping when applied to vertical surfaces or irregular surfaces, etc., even if dried at high temperatures, or to a water-base paint composition in which such an emulsion composition is used.
2. Description of the Related Art
Water-base emulsion compositions have water as a medium, and are used widely in adhesives, paints, etc., since they are safe from the viewpoint of flammability and toxicity. When emulsion compositions dry to form a continuous coating, moisture inside the emulsion volatilizes and water-insoluble emulsion particles bond with each other to form the coating, and plasticizers or high boiling solvents such as butyl cellosolve, etc., may be used as film forming auxiliaries to assist such coating formation. However, one problem has been that film forming auxiliaries have no effect if the paint film is thick or if drying temperatures are high, etc., and cracking or blistering, etc., of the paint film may occur. Such problems of cracking and blistering of the paint film are more likely to occur when the paint film is thick or is dried by applying temperature forcibly, etc., but they are problems that may occur at any time due to other factors such as changes in drying temperature, types of emulsion, etc., even if the paint film is thin and is dried at normal temperatures. Another problem has been that such aqueous emulsion compositions drip if dried at high temperatures when applied to vertical surfaces or irregular surfaces, etc.
Methods are known in which inorganic fillers such as activated carbon, calcium carbonate, etc., are added in order to prevent such problems and prevent cracking and blistering of the emulsion composition during film formation. In Japanese Patent Laid-Open No. HEI 10-324822, for example, a damping water-base paint composition is disclosed (Claim 1) that is a damping water-base paint composition including a resin emulsion and a filler as essential components, the resin emulsion being a resin emulsion in which: Tg is 10 to 50 degrees Celsius; a loss angle tangent (tangent delta) is greater than or equal to 1.5; and a mean particle diameter of a resin particle is 150 to 1,000 nm, the filler including 1 to 45 percent by weight (percent by mass) activated carbon. In paragraph [0020] of that patent laid-open, there is also a description to the effect that “fillers other than activated carbon include, for example: calcium carbonate, magnesium carbonate, barium sulfate, aluminium hydroxide, alumina, aluminium sulfate, calcium silicate, talc, clay, silica, carbon black, titanium oxide, mica, sepiolite, etc.”
Adding fibers such as natural fibers, synthetic fibers, etc., to an emulsion composition is also known. In Japanese Patent Laid-Open No. HEI 5-331390, for example, a paint composition is disclosed (Claim 1) into which is combined one species or more from: natural fibers; regenerated fibers; semisynthetic fibers; or synthetic fibers.
In addition, paints containing a thermosensitive gelatinizer constituted by a siloxane-polyoxyalkylene copolymer, and an ion cross-linking agent constituted by zinc oxide are known. In Japanese Patent Laid-Open No. HEI 6-157938, for example, a chipping resistant baked paint is disclosed (Claim 1) that has as essential components: a synthetic rubber latex and/or synthetic resin emulsion (A); a filler (B); a thermosensitive gelatinizer (C) constituted by a siloxane-polyoxyalkylene copolymer; and an ion cross-linking agent (D) constituted by zinc oxide.
Methods are also known in which thixotropic thickeners such as xanthan gum, or hydroxyethylcellulose, etc., are added in order to prevent dripping problems. In Japanese Patent Laid-Open No. 2000-34429, for example, a paint (Claim 1) is disclosed that contains high-viscosity xanthan gum that displays a viscosity of 3,500 to 25,000 mPa·s (B-type viscometer at 6 rpm, 25 degrees Celsius) in an aqueous solution having a xanthan gum concentration of 0.5 percent by weight (percent by mass).
Emulsions such as the damping water-base paint composition disclosed in Japanese Patent Laid-Open No. HEI 10-324822, in which inorganic compounds such as those described above are added as inorganic fillers, can be painted in a thick paint film, and blistering of the paint film can be suppressed to a certain extent during paint film drying, but such effects are insufficient, and in addition, one problem has been that they have almost no effect on cracking of the paint film. The paint composition described in Japanese Patent Laid-Open No. HEI 5-331390 also could not be said to have a sufficient effect on blistering and cracking during paint film drying. In addition, the chipping resistant baked paint described in Japanese Patent Laid-Open No. HEI 6-157938 could not be said to have a sufficient effect on blistering and cracking of the paint film, and in addition, other problems have been that in some cases effects do not appear at all due to the combination in the paint (the presence of ionic compounds such as salts, etc.) since ionic compounds are used, and the burden on the environment is increased during disposal since metal compounds are used. Furthermore, another problem has been that dripping cannot be prevented in the paint described in Japanese Patent Laid-Open No. 2000-34429 when dried at high temperatures since the viscosity decreases rapidly.